Tuesday, June 11, 2013

One last bit of seriously folded pumiceous obsidian. I had never made the connection before going through these photos, but does seem as if the frothy phase of this lava flow is more prone to this sort of deformation. On one hand, this makes a bit of sense: gas pockets would be easier to deform than high-silica lava. On the other, vitreous zones don't have the contrast these do, and may be folded, but not as visibly. And it seems questionable to think that a sample based on selected photos necessarily represents a realistic cross section of the actual features on the flow. In the end, I'll say the frothy component appears more likely to be folded, but it's something I should consciously look for (as opposed to notice in retrospect) next time I visit.